US3241648A - Device for producing code characters, for use with typewriters and similar characterprinting apparatus - Google Patents

Description

March 22, 1966 s. s. v. STENUDD 3,241,648

DEVICE FOR PRODUCING CODE] CHARACTERS, FOR USE WITH TYPEWRITERS AND SIMILAR CHARACTER PRINTING APPARATUS Filed June 9, 1.964 S Sheets-Sheet l FIGJ 'FIG .2I FlG.3 FIGA INVENTOR SVEN GUNNAR VALTER STENUDD BY W ATTOR N E YS March 22, 1966 s. v, s D 3,241,648

DEVICE FOR PRODUCING CODE CHARACTERS, FOR USE WITH TYPEWRITERS AND SIMILAR CHARACTER PRINTING APPARATUS Filed June 9, 1964 5 Sheets-Sheet 2 INVENTOR SVEN GUNNAR VALTER STENUDD ATTORNEYS March 22, I966 DEVICE FOR PRODUCING CODE CHARACTERS, FOR USE Filed June 9, 1964 (d) TM (h) VS 5. cs. v. STENUDD 3,241,648

WITH TYPEWRITERS AND SIMILAR CHARACTER PRINTING APPARATUS 5 Sheets-Sheet 3 INVENTOR SVEN GUNNAR VALTER STENUDD ATTORNEYS United States Patent 3,241,648 DEVICE FOR PRODUCING CODE CHARACTERS, FQR USE WITH TYPEWRITERS AND SIMILAR CHARACTER PRINTING APPARATUS Sven Guunar Valter Stenudd, Lidingo, Sweden, assignor to Ab Atvidabergs Industrier, Atvidabergs, Sweden Filed June 9, 1964, Ser. No. 373,707 Claims priority, application Sweden, June 11, 1963, 6,450/ 63 Claims. (Cl. 197-1) In intergated data processing procedures it is desired to produce a document readable by means of a machine, and at the same time to write an original document. A common example is an order routine where the order receiver concurrently with recording the order produces a perforated tape which then can be utilized as a base for stock book keeping, billing, business book keeping, etc. in completely automatically performed operations.

For producing the document readable by machine means typewriters have previously in most cases been used which are coupled topunch means of the type similar to that used for teleprinting. The decoding of the key functions is performed by means of a system of code bars which upon operation of the keys are displaced in various manners to produce a binary code representative of the typed character. Such machines, however, are expensive and slow in operation. Another possibility is to provide, for each key, a number of contacts corresponding to the code of said key. Due to the great number of contacts, however, such an arrangement will have little reliability. This reliability may be somewhat improved by providing only one contact for each key, but in such cases an extensive decoding network will be necessary, usually composed of semiconductor diodes.

All the arrangements referred to above are hampered by an additional drawback. The feeding-out of a code character is due to a key operation but there is no checking that the character has actually been printed. There may, for example, exist an obstacle in the path of the type bar. In such a case a code character will be fed out but since the operator does not observe any written character he will retype it and, consequently, a double feeding-out will result.

These drawbacks can be avoided by means of a device according to the invention. With such a device the feeding-out of the code characters is effected without any interposition of mechanic coding devices or electric contacts. Possibly, some contact may be present for producing code characters for such functions which have not been printed, e.g. spacing and carriage return. Further, the code character is not produced until the character has actually been printed.

The device according to the invention for producing code characters with typewriters and similar kinds of character printing apparatus, comprising a plurality of type bars, the character supporting parts of which during the travel towards a base move in a substantially common path by means of a type guide, is characterized by the fact that each type carrier, in association with the type supporting part, is provided with a number of perforations arranged in a predetermined pattern, a light source and a light sensing device being positioned on opposite sides of said common path, the light sensing device comprising a number of photo cells positioned in accordance with said pattern.

The invention will be further disclosed with reference to the accompanying drawings, where FIG. 1 is a perspective view of the key-bar and type guide of a typewriter provided with a device according to the invention. FIG. 2 is a detail of a type bar. FIGS. 3 and 4 are different modifications of the code printers mounted on the key- 3,241,648 Patented Mar. 22, 1966 bars. FIG. 5 shows the positional relationship of the perforations of the code plate and the photo cells, in the read-out position. FIG. 6 is a logic schematic representation of the electronic unit associated with the readout device. FIGS. 7a-h show the wave forms of different signals in the electronic unit.

In FIG. 1 a type bar section in a typewriter has been given the designation -1. In the slots 10 thereof the type bars 2 are arranged such that the top of the type bar, when actuated, passes through a type guide 7 centering the type 3 when it strikes against the platen or roller 11. The top of the type bars are bent such that the type will deliver characters along a vertical line when striking the platen. The type bar has behind its type a perforated part 5 which can either be integral with the type bar, or be a separate plate fixed to the type bar by clamping or soldering means. The perforated or punched part, i.e. the code plate 4, has a number of perforations 5 arranged in a predetermined pattern. On the section 1 a light source 8 is mounted for emitting a bundle of parallel light rays along the platen 11. At the opposite side of the type guide a photo cell device 9 is positioned coaxially with the light bundle. The photo cell device consists of a number of small photo cells, the operative parts of which are arranged in a pattern corresponding to the perforations in the code plate 4. When the type bar during its actuation moves against the platen the type and the code plate will enter the light bundle from the lamp 8, and just before the striking of the type against the platen the perforations of the code plate will register with the corresponding photo cell 9.

The code plate provided on each type bar has a predetermined combination of perforations, e.g. that shown in FIGS. 2 and 5, composed of the perforations Hl-H6. 'For example, H 1 may be open whereas all the other perforations may be closed to the letter A; H1 and H2 may be open to letter B, etc.

The perforation HP is provided for adding a parity bit to the code in order to make possible a parity check of the code character during the subsequent processing (punching, computer operation). When odd parity is used the perforation HP should be open to the letter B but closed to A, so that the sum of the open perforations is an odd number.

The perforation HS has an auxiliary function as it is utilized for producing a supervisory pulse for determining the instant the reading-out of the remaining perforations in the code plate is to take place, as described below.

The code plates may either be provided, by punching, with only the perforations desired, or they may be provided with the whole set of perforations in accordance with the chosen configuration, for example as shown in FIGS. 2 to 5. In the latter case, those perforations that should not transmit a signal are obstructed by means of a plastic plug or a lump of wax. It will then be very easy to modify the code for adaption to the special purpose of the utilization of the code signal.

The location of the perforations in the code plate may obviously be varied within wide limits. From space requirements reasons it is convenient to arrange the perforations in a symmetrical array in accordance with FIGS. 2 and 3. In FIG. 4 there is shown a further pos' sible positional arrangement.

FIG. 6 shows the electronic means used for producing the code characters. C1-C6, CP and CS are here representing the photo cells corresponding to the perforations H1-H6, HP and HS in the code plate. The photo cells C1-C6 and CP are connected to pulse shaping gates A1-A6 and AP. Each of the gates A1A6 is connected through respective or-gates Bl-B6 to an individual bistable register multivibrator D1-D6 while the gate AP is connected to a bistable multivibrator D8 through a parity bit generator PG and an or-gate B8.

The photo cell CS for producing the supervisory pulse is connected through a pulse shaping amplifier FS, an orgate G and an inhibiting gate H to the trigger input of a monostable multivibrator TM having a pulse duration sufficient for letting the perforation HS complete its passage past the photo cell CS during the return travel of the type after the reversal. The purpose of said multivibrator is to prevent a false reading-out when light strikes the photo cell CS during said return travel. The monostable multivibrator TM also triggers the monostable multivibrator TL which, in its turn, triggers the monostable multivibrator NP. The latter multivibrator transmits a zero-setting pulse of short duration to the registers Dl-DS while the first-mentioned circuit feeds an enabling pulse to the gates Al-A6, AP, so that the information read out by the photo cells can be transferred to the registers. The monostable multivibrator TM also operates to set the bistable multivibrators VF and VS; said multivibrators performing certain control functions and transferring the information contained in the registers to the data registering apparatus through the gates El-ES. For the purpose of producing code characters for the typographical functions of the typewriter, e.g. the tabulator TAB, line shift NL, back space BS, spacing MS and shift SG, which functions normally are not printed, contacts may be provided in association with the corresponding operation keys and be connected to a decoder KM for producing the code and feeding it to the registers Dl-DS. As to the shift function it has been assumed that the seventh bit of the code is reserved for indicating shifts. Thus, in shift operations it will be necessary to invert the parity bit to obtain the appropriate polarity. For checking the correct readingout of the code perforations a parity check circuit, known per se, is provided to prevent the information contained in the registers from being transferred to the registering apparatus if the parity check should disclose a non-correspondence.

The operation will now be described more in detail with reference to the pulse graphs shown in FIGS. 7a-h.

When a key-bar moves in its path towards the platen the type head will successively shield the photo cells C1-C6, CP, CS from the light rays of the lamp 8 starting from C3 and C4 in FIG. 5. The photo cell current will then be reduced as shown at the time in FIG. 7a.

.At the time t1 the last cell CS is shielded (FIG. 7b).

During the further motion of the type towards the platen the whole or a part of a perforation may pass a photo cell before the code plate arrives at a position in which the perforation HS registers with the cell CS. For example, the perforation HS may admit light to the cell CP. The signal then being produced is, however, prevented from reaching the register D8 as the gate AP is disabled as long as the multivibrator TL is reset or remains in its zero-position. At the time t2 the perforations H1-H6 start to admit light to the corresponding photo cells C1- C6, CP. In order to assure a maximum of light flow to the photo cells C1-C6, CP, the perforation HS is slightly displaced with respect to the photo cell CS so that this cell will be illuminated somewhat later than the remaining photo cells. That is because the multivibrator TM should normally be triggered before the full illumination of the photo cell CS to ensure that the deterioration with time of the lamp or the photo cell will not severely affect the reliability. FIG. shows the positional relationships of the cells and the perforations as seen in the direction towards the light source at the time t3 when the illumination of all photocells except CS is essentially at its maximum value.

Approximately at the time t3 the multivibrator TM is triggered by the pulse from the pulse shaping amplifier PS via the or-gate G and the inhibiting gate H. When TM is set the multivibrator TL is triggered and, in its turn, triggers the multivibrator NP. The pulse duration t3-t6 of the multivibrator TM is sutficient for preventing the perforation HS of the code plate from initiating a spurious triggering pulse to TM at the return of the code plate after the striking action. The multivibrator NP produces a pulse of a very short duration setting the registers D1-D7 to their zero-position. The multivibrator TL, being operative within the interval t4-t3, enables the gates A1A6 so that the information obtained from the photo cells can be operative to set the registers D1- D6. The register D7 is set by a contact of the shift key. The pulse from TL will also enable the gate AP to pass the parity bit so that it may be recorded in the register D8, possibly after having been inverted in the parity generator PB on account of a type shift.

At the time 14 of termination of the pulse from the photo cell amplifier PS, the type has advanced still nearer to the platen and is in its strike position. At this instant the pulse TM is allowed to pass through the gate N to trigger the bistable multivibrator VF. The multivibrator VF records that a striking action has been started, andas shown below-the multivibrator VF is reset within a predetermined time interval to enable the information stored in the registers Dl-DS to be transmitted to the registering apparatus.

The resetting of the multivibrator VF will be effected only when signals are present on all input terminals of the and-gate P; this will be the case when the multivibrator TM is set, a signal is obtained from PS, the information contained in the registers D1-D8 has the correct paritywhich is indicated by the parity check circuit PC-and a ready signal SH is delivered from the registering apparatus. At this resetting a pulse is produced which, after having been derived passes through the gate M enabled by the pulse TM, and sets the bistable multivibrator VS. Provided the registering apparatus delivers a ready signal SH the and-gate S is enabled, and a recording order OS is transmitted concurrently with the registers D1D8 being connected to the terminal conductors Tl-TS of the registering apparatus via the andgates El-ES.

In its set condition the multivibrator VS inhibits the gate I-I so that additional signals from the photo cell CS cannot trigger the monostable multivibrators TM. For example, this may occur with the pulse obtained at the time t7 when the leading edge of the pulse leaves the type position so that all of the light flow will fall upon the photo cells. In case the multivibrator VS has not been set at the time t7, it is true that TM and VP are triggered; VF, however, not having been reset at the appropriate time results in an error signal as described subsequently. The multivibrator VS is reset when the registering apparatus again delivers a ready signal SH.

By way of example only, the amplifier F8, in accordance with conventional practice, may include a differentiating circuit and a trigger circuit to produce the pulse at time t7. Thus, if the output of the photo cell CS remains high for a preselected time interval, the differentiating circuit will reduce the input to the trigger below the threshold value thereby producing the illustrated pulse. In the case of the pulses shown at times :3 and t5, the output from the photo cell CS does not remain high long enough to utilize the differentiating action of the amplifier, which behaves merely as a pulse shaper.

If no recording order OS is given after the initiation of a type striking action, this may be due to one of the following faults:

(1) The character has the wrong parity due to the registers Dl-D8 having missed a signal. Thus, the multi vibrator VF cannot be reset as one of the requirements for the and-gate P is absent. A possible reason for this fault may be foreign material in a perforation of the code plate or a deficient photo cell.

(2) The velocity of the type is too low so that the pulse produced by the photo cell CS during the return travel of the type will appear only upon the termination of the pulse TM, i.e. the time 15 occurs after t6. Also in this case one of the requirements for the gate P will be absent. This faulty operation may be due to an obstacle in the path of the type so that it will be decelerated and thus not able to develop a sutficient force to print a character on the paper. This control of the preventing of a recording action in the absence of a second pulse from the photo cell CS within a predetermined time interval also prevents false reading-outs due to the introduction of objects, as, for example, paper and erasing plates, in the path of the light rays.

(3) A time interval of too short a duration between two characters so that the registering apparatus will not have completed the writing of a character when the next type performs its striking action. Also in this case one requirement for the and-gate P will be absent so that the resetting of the multivibrator VF will be impossible. This type of defective function may be due to a faulty registering apparatus.

If the multivibrator VF has not been reset before the resetting of the multivibrator TM, an error indication will result as a consequence of the gate K allowing a stop signal OP to pass which in the first place actuates a magnet (not shown) which locks the keys of the typewriter, and in the second place disables the gate H thus preventing a triggering of the multivibrator TM. For continuing the Writing the multivibrator VF has to be reset manually either by means of a push button RVF or by operating the back spacer BS of the type writer; after that it will be possible to resume the writing.

Whenever one of the keys associated with the typographic functions TAB, NL, BS, MS is operated a signal VK will result which passes through the gates G and H and triggers the multivibrators TM, TL and NP. The signals received from the code matrix KM are instantly recorded in the registers E1438, and if the parity condition is satisfied and a ready signal SH is delivered the multivibrator VF is immediately reset, and a recording order is issued. As stated above, a wrong parity or the absence of a ready signal will result in an error indication.

Preferably the invention can be used with pulse controlled character printing apparatus, particularly with typewriters, for checking that the correct character has actually been printed. With the conventional pulse controlled typewriters which, for example, are used for writing characters delivered by computers, the movement of the type-bars is released by magnetic means; however, there is no checking that the correct type-bar actually strikes the paper. By comparing the control signal with the information received from a device it will be possible to obtain a confirmation of the fact that the correct character has actually been printed. Should the comparison indicate the printing of a wrong character retyping takes place or an error signal is delivered.

What I claim is:

1. A device for producing coded characters in typewriters and the like, comprising at least one movable mask having light permeable openings corresponding to a coded character, a light source, a plurality of photocells for reading the code represented by the openings of said mask when it is interposed between said light source and photocells, said openings have closed contours and permitting all of said photocells to be illuminated when said mask is in a first position, the illumination of at least one photocell being temporarily intercepted by the mask during movement of said mask from said first position to said interposed position, means utilizing the output of said one photocell when said mask is in the interposed posi tion for initiating read-out of said code, storage means, and gate means connected between said photocells and said storage means, said utilizing means enabling said gating means to pass signals from said photocells to said storage means only when said openings are positioned in a predetermined manner with respect to said photocells.

2. A device according to claim 1, wherein said typewriter comprises a plurality of type bars containing respective type characters thereon, there being an individual mask associated with each type bar, each of said masks being located immediately behind the character of its associated type bar, at least one of the openings in said masks causing said one photocell to be illuminated both before and after the type bar has caused the type character thereon to be printed.

3. Apparatus for use with a typewriter or the like wherein a movable type bar having thereon at least one character is adapted to be moved in a forward direction from an initial position to reproduce such character and wherein means are provided to return said type bar to its initial position, comprising a coded optical mask secured to said bar, a light source, photosensitive means situated in the path of said light source and responsive to the interposition of said mask in said path for producing coded signals representative of the character on the associated type bar, each of said masks being shaped to cause said photosensitive means to produce discrete electrical signals during the forward and return movements of the associated bar, means for transmitting said coded signals only when the delay between said discrete signals does not exceed a predetermined time interval, storage means, and means responsive to the occurrence of said first discrete electrical signal for coupling said coded signals to said storage means, said transmitting means being operative to cause readout of the information in said storage means.

4. Apparatus according to claim 3, including error checking means, and means responsive to said error checking means for inhibiting operation of said transmitting means in the event such coded signals contain an error.

5. Apparatus according to claim 3, including error indicating means for indicating when the delay between said discrete signals exceeds said predetermined time interval.

References Cited by the Examiner UNITED STATES PATENTS 2,350,893 6/1944 Hofgaard 1971 2,408,754 10/1946 Bush 1975 X 3,017,978 1/1962 Schulz 19717 3,032,163 5/1962 Flieg 1971.5

3,080,110 3/1963 Plaisance 234-l08 X 3,096,016 7/1963 Flieg 234108 ROBERT E. PULFREY, Primary Examiner.

EDGAR S. BURR, Assistant Examiner.

Claims (1)

1. A DEVICE FOR PRODUCING CODED CHARACTERS IN TYPEWRITERS AND THE LIKE, COMPRISING AT LEAST ONE MOVABLE MASK HAVING LIGHT PERMEABLE OPENINGS CORRESPONDING TO A CODED CHARACTER, A LIGHT SOURCE, A PLURALITY OF PHOTOCELLS FOR READING THE CODE REPRESENTED BY THE OPENINGS OF SAID MASK WHEN IT IS INTERPOSED BETWEEN SAID LIGHT SOURCE AND PHOTOCELLS, SAID OPENINGS HAVE CLOSED CONTROURS AND PERMITTING ALL OF SAID PHOTOCELLS TO BE ILLUMINATED WHEN SAID MASK IS IN A FIRST POSITION, THE ILLUMINATION OF AT LEAST ONE PHOTOCELL BEING TEMPORARILY INTERCEPTED BY THE MASK DURING MOVEMENT OF SAID MASK FROM SAID FIRST POSITION TO SAID INTERPOSED POSITION, MEANS UTILIZING THE OUTPUT OF SAID ONE PHOTOCELL WHEN SAID MASK IS IN THE INTERPOSED POSITION FOR INITIATING READ-OUT OF SAID CODE, STORAGE MEANS, AND GATE MEANS CONNECTED BETWEEN SAID PHOTOCELLS AND SAID STORAGE MEANS, SAID UTILIZING MEANS ENABLING SAID GATING MEANS TO PASS SIGNALS FROM SAID PHOTOCELLS TO SAID STORAGE MEANS ONLY WHEN SAID OPENINGS ARE POSITIONED IN A PREDETERMINED MANNER WITH RESPECT TO SAID PHOTOCELLS.

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